Characteristics of Zinc and copper metabolism and nutrition in healthy elderly subjects will be explored with the aid of stable isotopes of zinc and copper. Results will be compared with identical studies conducted in healthy young adults. Three major areas will be investigated: (a) comparison of the absorption of intrinsic and extrinsic tags of zinc, based on wheat biologically labeled with 68Zn and 65Cu, at adequate zinc and copper intakes, (b) an exploration of the adaptations of zinc absorption and utilization to low zinc intakes and (c) an examination of the effects of changes in the dietary ratio (w/w) of copper; zinc or the absorption and retention of zinc and copper, using 70Zn and 65Cu as stable isotope probes.